Phase Equilibrium and Density of CO2 + Acetic Acid Systems from 308.15 to 338.15 K and 15 to 45 MPa.

Abstract

Using a high-pressure phase equilibrium apparatus and vibrating-tube densimeter, phase transition pressures of CO2 (1) + acetic acid (2) binary systems with x2 = 0.000, 0.107, 0.163, 0.222, and 1.000 were measured under temperatures from 308.15 to 338.15 K. Besides, the densities at the same composition and temperature under pressure from 15 to 45 MPa were also detected, and the volumes of mixing (ΔVm) were calculated. Three prediction models (SRK EOS, PC-SAFT EOS, and TS model) were introduced to predict and correlate the density of binary systems, which was found to have positive relationships with temperature and acetic acid concentration and a negative relationship with pressure. Thereinto, the variation trend of CO2 density with pressure tends to be flat under high pressure, and which of acetic acid density increased linearly with pressure. ΔVm are negative, and their absolute value increases with the increase of temperature and the decrease of pressure. The work herein could provide a theoretical guide and basic data for supercritical CO2 extraction technology and CO2 application in oil field development.